Process of treating zinc.



S. FRANK. PROCESS OF TREATING ZINC. APPLICATION FILED JUNE 14,1909.

935,900. v Patented Oct. 5, 1909.

PATENT OFFICE.

SALOMON FRANK, OF FRANKFORT-ON-THEMAIN, GERMANY.

PROCESS OF TREATING ZINC.

Specification of Letters Patent.

Patented Oct. 5, 1909.

Application filed June 14, 1909. serial'No. 502,116.

To all whom it may concern:

vBe it known that I, SALOMON FRANK, a

subject of the King of England, and resi-- dent of Frankfort-on-the-Main, Germany,

. have invented certain new and useful Improvements in Processes of Treating Zinc, of WhlCll the followmg 1s a specification.

My invention relates to improvements in a process of treating zinc, and to the new prodnot produced thereby. And the object of the improvements is to impart to the zinc the properties of brass, such for example as high strength, great malleability and flexibility, and particularly those properties which permit the metal to be readily worked on machine tools by means of'cutting tools, which properties could heretofore be imparted to the zinc merely by mixing the same with copper and, for certain purposes, with tin, WhlCll metals however, are comparatively expensive.

With this object in view, my imprbved process consists in compressing the zinc in the manner described hereinafter, and forming the same into rods, or directly into finished articles.

For the purpose of explaining the invention several examples of apparatus adapted for carrying the same into effect have been shown in the accompanying drawing in which the same letters of reference have been used in all the views to indicate corresponding parts.

In said drawing Figure 1, is a cross-section of the die and punch of a press, Fig. 2, is a cross-section of the same showing the block of zinc while being subjected to my improved process, and Figs. 3 and 4, are cross-sections of modified forms of the die.

' In carrying out my improved process, I proceed as follows: A block a of zinc of the usual properties is first slightly heated to a temperature of from 30 to 80 degrees centigrade, which is preferably done in a water bath. After being thus preheated it is placed into the die I) of a press of that class as has heretofore been used in the manufacture of lead pipes or bars from a block by means of the pressing process. In said press the zinc is exposed to a pressure of 6000 kilograms per square centimeter (90,000 pounds per square inch) or more. Thereby the coarse crystalline structure of the ordinary zinc is transformed into a very fine crystalline structure, and when thus transformed the zinc assumes the properties of the brass. By thus treating the zinc, its

strength is multiplied. Under ordinary circumstances the tensile strength is increased to 1000 kilograms per square centimeter (23,000 pounds per square inch), which can be increased to 2000 kilograms per square centimeter (29,000 pounds per'square inch), its extension being from 20% to 70% while the ordinary zinc has almost no extension at all and a tensile strength of less than 8 kilograms per square centimeter (120 pounds per square inch). Furthermore, by thus transforming the coarse crys alline structure of the zinc into a fine crystalline structure, the zinc can readily be Worked in machinetools. In carrying out the process, the speed of the Zinc being pressed through the aperture of the die must be sufficiently small to prevent the zinc from being heated by friction above the aforesaid temperature of 80 degrees centigrade. Such an undue increase of the temperature would injuriously affect the structure of the zinc, so that it could not so readily be worked.

In carrying out the process, it is of importance, that neither before nor during the same the zinc is heated to the temperature of from 120 to 150 degrees centigrade which is usual in warm pressing or rolling zinc, because such a temperature would render the zinc unsuitable for the purpose described. The temperatures of 30 and 80 degrees centigrade are the upper and lower limits for securing the best results.

A suitable pressure will be obtained when using a die the opening of which has a sharp cut edge, and in which the cross-section of the opening is in .a certain large ratio to the cross-section of the block of zinc, and I have found that a ratiov of 1 to 15 gives good re-' sults. An example of such a structure is shown in Figs. 1 and 2, in which 0 indicates the edge of the aperture of the die. When using an opening of larger cross-sectional area the discharge edge over which the zinc is forced must be rounded, as shown at n in Fig. 4. A suitable pressure on the zinc will also be obtained, if the inner bottom of the die is made with a funnel like tapering wall, as shown in Fig. 3. By properly rounding the edge of the aperture of the die and by properly tapering the bottom of'the same the resistance of the block of zinc being pressed can be regulated in sucha way, that the minimum pressure required for transforming the structure of the zinc is obtained.

The resistance at the discharge end of the die must be raised as described, because the zincunder pressure has the tendency to flow out of the die with great speed and under a small pressure .without transforming its structure. In this case, the effect aimed at would not be produced, because under a small pressure a metal similar to the brass can not be produced.

I-Ieretofore by means of a press of the character indicated tubes and rods of various kinds have been made by forcing tin, copper, or other semi-hard metals in a cold or heated state through the die of the press, in which case, however, the only object was to shape the metal. In such processes it was immaterial, whether the structure of the metalwas transformed only near its surface, or if the transformation of the structure extended to the inner parts of the metal. By my improved process, which exclusively relates to the treatment of a zinc of certain properties, the structure of the metal is not only transformed near its surface, but also through its inner parts, whereby a metal of entirely different physical properties is produced, which metal may be designated as an allotropic modification of the ordinary zinc, and which does not show the ordinary properties of zinc. Furthermore in 'the old process indicated above the metal was discharged from the press under as small a pressure as possible in order to save energy and to spare the tools. My improved process however requires a pressure which is considerably larger than that used before in the old process.

I claim:

1. The herein described process of treating Zinc which consists in, forcing the zinc at a temperature of not more than. 80 degrees centigrade and under a minimum pressure. of (5000 kilograms per square centimeter through an aperture.

2. The herein described process of treating zinc, which consists in heating the zinc to a tem erature of from 30 to '80 degrees centigra e, placing the same into the die of a press, and forcing the same through the discharge opening of said die under a minimum pressure of 0000 kilograms per square centimeter.

3. The herein described process of treating zinc, which consists in causing the zinc to flow under a minimum ressure of 6000 kilograms per square centimeter and at a temperature of not more than 80 degrees centlgrade.

4. The herein described new product consisting of a zinc of fine crystalline structure,

and having the physical properties of brass,

and which is obtained by causing zinc to flow under a minimum pressure of 6000 kilograms per square centimeter and at a temperature of not more than 80 degrees centigrade.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

SALOMON FRANK.

Witnesses JEAN GRUND, CARL GRUND. 

